如何检测蓝牙是否连接？

Question

我使用此代码在蓝牙设备连接或断开连接时收到通知，但是，它不会检查蓝牙设备是否作为音频设备连接

// ...
    IntentFilter filter1 = new IntentFilter(
            BluetoothDevice.ACTION_ACL_CONNECTED);
    IntentFilter filter2 = new IntentFilter(
            BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
    IntentFilter filter3 = new IntentFilter(
            BluetoothDevice.ACTION_ACL_DISCONNECTED);
    this.registerReceiver(BTReceiver, filter1);
    this.registerReceiver(BTReceiver, filter2);
    this.registerReceiver(BTReceiver, filter3);
}

// The BroadcastReceiver that listens for bluetooth broadcasts
private final BroadcastReceiver BTReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();

        if (BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)) {
            // Do something if connected
            Toast.makeText(getApplicationContext(), "BT Connected",
                    Toast.LENGTH_SHORT).show();
        } else if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) {
            // Do something if disconnected
            Toast.makeText(getApplicationContext(), "BT Disconnected",
                    Toast.LENGTH_SHORT).show();
        }
        // else if...
    }
};

如何检测 A2DP、btA2dp 音频设备？

Answer 1

您应该注册三个广播以跟踪蓝牙设备连接：

// ...

IntentFilter filter1 = new IntentFilter(
    BluetoothAdapter.ACTION_STATE_CHANGED);
IntentFilter filter2 = new IntentFilter(
    BluetoothAdapter.ACTION_CONNECTION_STATE_CHANGED);
IntentFilter filter3 = new IntentFilter(
    BluetoothA2dp.ACTION_CONNECTION_STATE_CHANGED);

// ...

switch (action) {
    case BluetoothAdapter.ACTION_STATE_CHANGED:
        // Bluetooth state changed (turned on/off)
        break;
    case BluetoothAdapter.ACTION_CONNECTION_STATE_CHANGED:
        // Bluetooth connection state changed (device got connected/disconnected)
        break;
    case BluetoothA2dp.ACTION_CONNECTION_STATE_CHANGED:
        // Bluetooth device gained/lost it's state as the media audio device
        if(intent.getIntExtra(BluetoothA2dp.EXTRA_STATE, -1) == BluetoothA2dp.STATE_CONNECTED) {
            Toast.makeText(context, "A2DP device connected!", Toast.LENGTH_LONG).show();
        }
        break;
}

来自BluetoothA2dp.ACTION_CONNECTION_STATE_CHANGED的文档：

此意图将有 3 个附加功能：

EXTRA_STATE - 配置文件的当前状态。

EXTRA_PREVIOUS_STATE- 配置文件的先前状态。

EXTRA_DEVICE - 远程设备。

EXTRA_STATE 或 EXTRA_PREVIOUS_STATE 可以是 STATE_DISCONNECTED 中的任何一个， STATE_CONNECTING, STATE_CONNECTED, STATE_DISCONNECTING.

要检查 A2DP 设备是否在流式传输，请注册BluetoothA2dp.ACTION_PLAYING_STATE_CHANGED 广播。

来自BluetoothA2dp.ACTION_PLAYING_STATE_CHANGED的文档：

此意图将有 3 个附加功能：

EXTRA_STATE - 配置文件的当前状态。

EXTRA_PREVIOUS_STATE - 配置文件的先前状态。

EXTRA_DEVICE - 远程设备。

EXTRA_STATE 或 EXTRA_PREVIOUS_STATE 可以是 STATE_PLAYING 中的任何一个， STATE_NOT_PLAYING.